Answer:
7
Step-by-step explanation:
form a proportion 
12/2=42/x 
cross multiply 
12x=84
x=7
 
        
                    
             
        
        
        
Answer:
c=-5
d=1
Step-by-step explanation:

I'm going to reorder the left-hand side.  Multiplication is commutative.

Since the bases are the same in 
 and the operation is multiplication, I'm going to add the exponents giving me:

So this implies we have two equations to solve:
 and 
So the first equation can be solved by dividing both sides by 4 giving you 
.
The second equation can be solved by subtracting 2 on both sides giving you 
.
 
        
             
        
        
        
Answer:
(2, - 3 )
Step-by-step explanation:
Given the 2 equations
2x - 3y = 13 → (1)
x + 2y = - 4 → (2)
Rearrange (2) expressing x in terms of y by subtracting 2y from both sides
x = - 4 - 2y → (3)
Substitute x = - 4 - 2y into (1)
2(- 4 - 2y) - 3y = 13 ← distribute and simplify left side
- 8 - 4y - 3y = 13
- 8 - 7y = 13 ( add 8 to both sides )
- 7y = 21 ( divide both sides by - 7 )
y = - 3
Substitute y = - 3 into (3) for corresponding value of x
x = - 4 - 2(- 3) = - 4 + 6 = 2
Solution is (2, - 3 )
 
        
             
        
        
        
Answer: m∠BCE = 63°
               m∠BAD = 76°
Step-by-step explanation:
Problem 1:
Given
m∠BEC = 90°
m∠EBC = 27°
Total = 117°
Solution:
Subtract 180° - 117° = m∠BCE = 63°
Problem 2:
Given
m∠ADE = 52°
m∠ABE = 52°
Total = 104°
Solution:
Subtract 180° - 104° = m∠BAD = 76°